Very interesting, really. I would like to know which of the shown scenarios would be closest to the ocean reality. Also, with the landing gear up the orbiter landed quite "smoothly" every time. The question is what would happen to the crew — the braking forces must have been enormous and if I remember well the ditching the water was thought to be unsurvivable?

Headshot

I also find this very interesting. I wonder how long the orbiter would stay afloat after one of these landings?

Hart Sastrowardoyo

Isn't the 205K weight extremely light for a flight orbiter? I mean, Enterprise alone weighed 171K with its main engines installed, but those main engines had no plumbing and as well, the payload bay had no associated equipment - not to mention that there's no including in that 171K as well of a five-to-seven astronaut flight crew with its life support equipment. At the very least.

Robert Pearlman

Columbia was 158,289 pounds at rollout and 178,000 pounds with main engines installed (source).

Endeavour was 151,205 pounds at rollout and 172,000 pounds with main engines installed (source).

keith.wilson

Even with waves in the tank it still looks unrealistically calm to me. If a crew was onboard when it ditched it looks like it might have been survivable provided the sea was mirror calm, the gear was up and the exterior of the orbiter was undamaged.

However I believe the plan was for the crew to blow off the hatch on the side of the crew cabin. Then they would release a pole that extends through the hatch opening. Each crew member would hook onto the pole and, one at a time, slide down the pole and then parachute into the ocean to await recovery.

p51

The idea that ditching an orbiter would be this smooth is downright comical, to me. There’s no way a belly-landing like that would play out in real life without the thing probably breaking up and drowning the crew. You're fighting wave action, and there's almost no chance you could ditch a craft like that between troughs in the waves due to the type of approach you'd need to make against a crosswind. Ask any glider pilot.

Experiences in ditching various aircraft in the military play this out. Look at the B-17 from WW2, for example. Pilots would tell you that landing one on level ground with the wheels up could be considered easier than landing with the gear down (other than worrying about the props breaking off the spinner hubs and coming into the plane), it's quite controllable in a belly-landing. The same plane is a brick landing in water. Watch films of planes ditching, they all stop really hard. So what happens in the interior? Seats break off, and stuff goes flying everywhere. I good griend of mine ditched two military planes in the big one, and both times the plane came to an immediate halt and hilarity did NOT ensue.

Structurally, I can't imagine an orbiter would keep its wings on in such a situation. And with the hatch so low on the side of the crew compartment, it'd be really tough to get out with all that water streaming in from there.

Part of the Return To Launch Site (RTLS) abort mode was of course coming back over the water and the people I’ve talked with all said that the orbiter would probably have ditched into the Atlantic had they tried that. I worked with NASA on a counter-terrorism exercise several years ago and I was told in no uncertain terms that NO attempts at a manned ditching of an orbiter would be attempted (I was dealing with it in the context of someone damaging the stack on liftoff with a surface-launched weapon and what would happen next). The group I was with had a few USAF pilots and all agreed that bailing out would be the preferred mode, which one said he’d confirmed with a mission commander at some point early on in the planning phase of the exercise (I never found out who this was). One person told me that a RTLS was considered for STS-1 at an early stage in planning but apparently was killed by John Young once he heard of it, but I can’t confirm this.

Hart Sastrowardoyo

quote:Originally posted by Robert Pearlman:Columbia was 158,289 pounds at rollout and 178,000 pounds with main engines installed. Endeavour was 151,205 pounds at rollout and 172,000 pounds with main engines installed .

OK. But STS-135, with its crew of four, had just a payload weight of 31,015 pounds, according to the press kit. Assuming (probably wrongly) that Atlantis' weight is equivalent to Endeavour's weight, that's just 2,000 pounds alloted for crew, life-support and middeck experiments to reach a 205K weight.

(EDIT: And with a crew of four, assume that each crewmembers weighs about 150 pounds each, or 600 pounds total, and that each ACES, including parachute and survival systems, weighs about 90 pounds each, or another 360 pounds. That's 1,040 pounds left over for middeck experiments and whatever else.)

Was the 205K weight an average, or a best-case scenario? It seems like the 205K weight was on the light side for a "typical" shuttle mission. Most shuttle flights had between five and seven crew alone, which would add some weight just for that.

Greggy_D

I can't fathom how these tests were even slightly comparable to real life. Different weights, different materials, etc.

p51

I agree fully. Most tests of this type were done with solid representations of the airframe itself. I'd bet my life savings that this model was orders of magnitude sturdier than a real orbiter would have been in such a case.

onesmallstep

All this makes the successful ditching of a US Airways jet on the Hudson River four years ago by Capt. Chesley Sullenberger all the more remarkable. For a shuttle orbiter crew, bailing out v. ditching was a choice between the lesser of two evils.

Jay Chladek

Guys, just remember this is more of a study of the behavior of an orbiter shape in a simulated watertank with controlled factors. They are providing data points which presumably would be combined with other data collected elsewhere to provide a whole picture of how an orbiter "might" behave.

From what I see, shape-wise it could have worked. But whether or not the shuttle's TPS and aircraft structure could have survived the impact forces can't be answered here as the video is not studying that (it is up to the structural and materials engineers to try and answer those questions). If the gee loads were low enough, I think the crew would have survived the ditching.

Personally though, I would be WAY more concerned with what might happen if hypergolic fuel residue from the Forward RCS and/or the OMS pods leaked next to where the crew were trying to inflate their rafts or life preservers. THAT could make an already bad day even worse.

GoesTo11

Sorry for being late to this, but I'd like to know if anyone with aerospace engineering experience/expertise might still care to weigh in on the correlation of these tests to potential reality.

I have no engineering background, and to me these clips just look like a big model airplane "landing" in a wading pool. It strikes me as a "check the box" exercise, and from what I've read and heard, actual shuttle astronauts — particularly those with a Navy aviation pedigree — didn't regard an actual orbiter ditching at sea as a survivable event. Thoughts?

GACspaceguy

I have seen a number of these ditching videos and you often wonder if the time came could it be done. I know that a Gulfstream GIV ditched in France and all on board survived. Also that Captain "Sully" Sullenberger managed to dead stick his A320 in the Hudson River. Therefore the possibility does exist for this to be a plausible survivable scenario.

GoesTo11

True enough, but whether it's a G-5 or an Airbus airliner, they're still conventional aircraft designed to optimize lift. The shuttle orbiter was another animal... I know crews simulated these ditching scenarios countless times, and I'd be curious to know both how slow they got their vertical descent rate, and how many times the computer told them they ditched structurally intact.

GACspaceguy

quote:Originally posted by GoesTo11:True enough, but whether it's a G-5 or an Airbus airliner, they're still conventional aircraft designed to optimize lift.

Understand that in a dead stick landing, even for conventional aircraft, all high lift devices (slat, flaps) are not deployed and thus landing/stall speeds are much higher.

With the shuttle, one would assume that while the initial approach would be conventional the ditching procedure after the flare would maximize energy bleed off so that the ditching speed could be significantly different than the landing speed.

I would think this emergency procedure would be similar to the Return To Launch Site (RTLS) abort and the Transoceanic Abort Landing (TAL). Simulated but never needed and in each case a "sporty" event (quoting Jack Lousma who said that in the early days before some of the software improvements, he was more concerned with the TAL than the RTLS abort).

(By the way, a GV has never had to ditch.)

ea757grrl

quote:Originally posted by GACspaceguy:I would think this emergency procedure would be similar to the Return To Launch Site (RTLS) abort and the Transoceanic Abort Landing (TAL).

I forget which astronaut described it this way, but he characterized RTLS as (if I recall correctly) "two miracles followed by an act of God."

dom

It appears that trying to land the shuttle on water with the wheels down would have been a seriously bad idea! Does anyone know if the shuttle's wheels could be retracted once they deployed or did they 'lock' into place for landing?

Robert Pearlman

With regards to this being a "survivable" event, there didn't necessarily need to be people onboard the orbiter.

If I recall correctly, up until some point in the space shuttle's development, NASA was intending the orbiter to have an autonomous (or remotely controlled) landing capability, in part to allow landings when visibility was poor.

Working from memory, it was the pilot astronauts in the corps that worked to keep this option off the table, so as to not negate the need to have pilots aboard.

But the orbiters kept that capability throughout their 30 years of service and, after the loss of Columbia, NASA enabled it as a possibility — specifically for a ditch scenario — by flying a cable that would connect the flight deck controls to additional CPUs on the middeck.

I don't know if it was ever sophisticated enough to execute a level landing on water, but that's a matter of software, rather than hardware.

quote:Originally posted by dom:Does anyone know if the shuttle's wheels could be retracted once they deployed...

Once deployed, the gear could not be retracted in flight. This was one of the justifications the pilot astronauts used to negate the idea of an autonomously-controlled landing.

GoesTo11

quote:Originally posted by GACspaceguy:(By the way, a GV has never had to ditch.)

Fred, thanks for the clarification. By the way, I had no idea whether or not a G-V had ever ditched on water or not, I just threw it out as a hypothetical.

I'd still be very interested to know the "success" rate of simulated abort scenarios (RTLS, TAL, etc.), including ditching at sea, and anyone's thoughts as to how realistic these outcomes were. "Two miracles followed by an act of God" sounds about right to me.

Also, Robert's post brings up another discussion, one that I can't believe hasn't already been explored here... I've never been quite clear about to what extent the shuttle could have operated autonomously. I realize it was never in the cards for all the obvious reasons, but how much software and operational optimization would it have taken to fly an un-crewed shuttle mission? Was it even possible? Again, sorry if I missed this in another discussion thread.

Robert Pearlman

quote:Originally posted by GoesTo11:I've never been quite clear about to what extent the shuttle could have operated autonomously.

Probably an oversimplification, but one astronaut told me the only thing the onboard computers could not do was deploy the landing gear. Everything else could have been remotely or autonomously controlled.

(Assuming, of course, that "everything else" meant launch, enter orbit and return to Earth. Any on-orbit activities required a crew.)

The cable flown on the final missions, STS-114 onward, allowed for the gear to be deployed remotely, too.

Hart Sastrowardoyo

I no longer have the book, but in one of Dennis Jenkins' book about the space shuttle he mentions Rockwell proposing an automated orbiter kit (A-OK - gotta love acronyms!) which would enable an orbiter, most likely Columbia, to launch and land without any crew. NASA rejected it.

I also seem to remember that an Autoland capability was intended for the shuttle, and indeed, there was one mission (mid-'90s?) where it was slated/proposed to be tested. (If I recall correctly, 10 such landings needed to be made before the system could be declared operational.) But for whatever reason, that never happened. (And I think it's the air data probe that needed to be extended manually, not the landing gear. But I could be wrong.)